The present invention relates to improvements in disposable liners for containers, and, in one particular aspect, to unique and improved impervious skin-tight plastic liners, for paint buckets and the like, which retain a desired shape despite thinness of side and bottom walls resulting from vacuum-forming from thermoplastic sheet material, and which may be readily inserted into and removed from a container because of venting afforded by side-wall ribs, and which may be releasably snaplocked in place and kept free of drip and pour contaminations by a relatively stiff overhanging rim having several indentations.
It has of course been generally well known to line containers with inexpensive disposable plastic liners, and the common soft flat plastic bags which may be opened and draped over and inside wastebaskets and the like comprise one familiar example. Imperviousness, and ease of cleaning and disposing of contents have been prime considerations, and liquid-proof linings have been provided for such diverse items as foamed-plastic containers (U.S. Pat. No. 3,144,167), garbage pails (U.S. Pat. No. 1,484,606), and drums for chemicals (U.S. Pat. No. 3,167,210). The latter patent, involving closed drums with top filler necks, disclosed fluted ribbing to impart stiffness to side walls of a plastic drum liner, and, in another case (U.S. Pat. No. 3,940,052), the base of a drum liner has been made stiff, and, in a yet further case (U.S. Pat. No. 3,027,444), a liner fitted within a fiber industrial drum has been caused to have progressively increasing thickness from top to bottom. Holes near the upper end of a flexible bag have served to vent a garbage can while it was being lined (U.S. Pat. No. 2,092,969), and a collapsible paint bucket and its liner have both been collapsed in a controlled manner to exclude air as the contents diminished (U.S. Pat. No. 3,173,573). Flexible bags, reinforced with a metal frame and having an upper tie-off, have also been proposed for lining a paint container and sealing a brush in place (U.S. Pat. No. 3,905,476). It has further been known to frictionally fit and hold the rim of a plastic cup lid (U.S. Pat. No. 4,026,459).
Professional decorators routinely employ open-topped metal paint buckets of predetermined sizes to hold desired quantities of paint, and, although such containers are relatively inexpensive, their costs are not negligible, and substitute non-metallic construction material such as paperboard has been introduced in an effort to reduce investments in such items. In accordance with the present teachings, a conventional sturdy metal paint bucket may be used and re-used, over and over again, without need for intermediate cleaning or drying, and without regard for color or other contaminations, by fitting the bucket with a very thin low-cost disposable plastic liner. Although it might at first seem to be a straightforward matter to implement such a concept, there are numerous complications which interfere. For example, the thin pliable-bag type liner, which immediately comes to mind, is bothersome to open, handle and fit in place, and it tends to wrinkle, to sag from its intended position, and to tear and puncture readily. If, on the other hand, the liner is made rather stiff, it tends also to be thicker and more costly to make, and it resists seating and unseating if it is of tight form-fitting proportions. Further, any leakage between the bucket and liner, such as may occur as the result of brush-wiping and dripping, tends to cause the two to adhere and can lead to need for bothersome cleaning to prevent subsequent contaminations and poor fit of other liners.